/**
* Get a unique key for sorting this node.
*
* Used to sort nodes into tree order. That is top to bottom and then left
* to right.
*
* @return string
*/
public function sortKey()
{
if ($this instanceof RootNode) {
return spl_object_hash($this);
}
if (!$this->parent) {
return '~/' . spl_object_hash($this);
}
$path = $this->parent->sortKey() . '/';
$position = 0;
$previous = $this->previous;
while ($previous) {
$position++;
$previous = $previous->previous;
}
$path .= $position;
return $path;
}
